The present invention generally relates to a grommet for not only protecting a wire bundle inserted through a hole of a body of a motor vehicle but imparting waterproofness to the wire bundle, which is made of an elastic material and more particularly, to a grommet including a grommet body made of an elastic material and a rigid clamp fitted into an annular groove formed in the grommet body, in which shape of the grommet body is improved such that the clamp can be easily fitted into the annular groove.
Conventionally, grommets of this kind are generally made of an elastic material such as rubber in view of protection and waterproofness of the wire bundle. However, the grommets formed only by rubber have such a drawback in that it is difficult to mount the grommets on a vehicle body. In order to eliminate this drawback, a grommet was proposed in which a rigid clamp made of synthetic resin is fitted into a grommet body made of rubber such that the grommet is mounted on the vehicle body by using the clamp.
For example, FIG. 1 shows a known grommet including a grommet body 2 made of rubber and a clamp 3 made of synthetic resin. In the grommet body 2, a cylindrical portion 2a receiving closely an outer periphery of a wire bundle 1, a radially outwardly extending flange 2b disposed at one end of the grommet body 2, an annular groove 2c formed on an inner face of an outer peripheral portion of the flange 2b and a seal lip 2d projecting from a distal end of the annular groove 2c are formed integrally. On the other hand, in the clamp 3, a cylindrical portion 3a having an inside diameter larger than an outside diameter of the wire bundle 1, a disklike seal lip clamping portion 3b extending radially outwardly from one end of an outer periphery of the cylindrical portion 3a, a mounting portion 3c extending radially outwardly from the other end of the outer periphery of the cylindrical portion 3a and a contact portion 3d disposed on the mounting portion 3c are formed by integral molding. The seal lip clamping portion 3b of the clamp 3 is fitted into the annular groove 2c of the grommet body 2 such that the clamp 3 is mounted on the grommet body 2. The seal lip 2d of the grommet body 2 is pressed against an outer side face of a wall 4 of a vehicle body, while the mounting portion 3c of the clamp 3 is fitted into a hole 4a of the wall 4 so as to bring the contact portion 3d of the clamp 3 into contact with an inner side face of the wall 4 such that the clamp 3, i.e., the known grommet is mounted on the wall 4.
As shown in FIG. 2, if the seal lip 2d can be returned in the direction of the arrow X2 in a state in which the entire seal lip 2d is turned up in the direction of the arrow X1 such that the seal lip clamping portion 3b of the clamp 3 is pressed against an inner side face 2b' of the flange 2b, the seal lip clamping portion 3b of the clamp 3 can be easily fitted into the annular groove 2c of the grommet body 2.
However, in the known grommet, a tension of the rubber forming the grommet body 2 is large. Therefore, even if the entire seal lip 2d is turned up in the direction of the arrow X1, the seal lip 2 readily returns to the original state. Accordingly, the seal lip clamping portion 3b is fitted into the the annular groove 2c while the seal lip 2d is being partially turned up in the direction of the arrow X1. Consequently, working efficiency of operation of mounting the clamp 3 on the grommet body 2 is poor and thus, a long time period is required for performing the operation.
The present inventors have found that the above mentioned problem of the known grommet, wherein the seal lip 2d returns to the original state by its tension even if the seal lip 2d is turned up, is incurred by the construction of the grommet body 2 in which the flange 2b is formed by a thin wall, an outer peripheral wall 2e of the flange 2b is formed by a thick wall and an outer peripheral face 2f of a bent portion connecting the flange 2b and the outer peripheral wall 2e has a large radius of curvature.